1. Field of the Invention
The present invention relates to an exposure apparatus, a method for manufacturing thereof, an exposure method, and a method for manufacturing a microdevice. In particular, it is related to a multi-scanning projection exposure apparatus, a method for manufacturing thereof, method for exposing, and method for manufacturing a microdevice, which projection exposes the pattern of a mask onto a photosensitive substrate while moving the mask and the photosensitive substrate relative to a projection optical system that is comprised, for example, of a plurality of reflection/refraction projection optical modules.
2. Related Technical Background
In recent years, the use of liquid crystal display (LCD) panels have become predominant as display components of devices such as word processors, personal computers and televisions. LCD panels are fabricated by patterning transparent thin electrodes onto a substrate in a desired shape using a photolithographic technique. As the apparatus for this photolithographic step, a projection aligner is utilized to projection expose an original image pattern that is formed on a mask onto a photoresist layer on a substrate using a projection optical system.
Recently though, there is greater demand for the size of these LCD panels to be made larger, and in order to meet this demand, an increase in the size of the exposure region in this type of aligner is also desired. In order to increase the size of this exposure region, so-called multi-scanning projection aligners have been proposed. In the multi-scanning projection aligner, projection exposure of the pattern of a mask is performed while moving a mask and a substrate relative to a projection optical system that is comprised of a plurality of projection optical modules. It is noted here that the projection optical module may also be referred to as a projection optical unit. In the following, this is also included in the definition of a projection optical unit.
Also, in the multi-scanning projection aligner thus formed, the light that is supplied from the illumination optical system is incident to each projection optical module via a mask. The light that is incident to each projection optical module reaches the substrate after it passes through the lenses of each projection optical module. A portion of the light that is reflected on the surface of the substrate becomes return light and again passes through the lenses of each projection optical module.
In this manner, when the transmitted light from the mask and the reflected light from the substrate pass through the lenses of each projection optical module, a portion of the light is absorbed by the lenses. As a result, it may be considered that the optical characteristics of each projection optical module, for example the positioning of the image planes, thereof in a focusing direction, may change because of the heat deformation due to optical absorption of the lenses that form each projection module.
In this case, as described in detail below, the image plane of each projection optical module is not flat, but is actually curved due to curvature of field. And, the heat deformation of the lenses due to optical illumination causes not only the fluctuation in the image plane positioning for each projection optical module, but also changes in the curvature of field. Accordingly, even if, for example, the center or the mean positioning of the image plane of each projection optical module are controlled to be the same height, the portions that contribute to formation of the partially overlapping exposure region in the image planes of the projection optical modules that are next to each other are separated in a certain focusing direction, thus making it impossible to perform satisfactory overlapping exposures.
An object of the present invention is to provide an exposure apparatus, an exposure apparatus manufacturing method, and an exposure method capable of preventing changes in optical characteristics due to heat in projection optical modules caused by light.
Another object of the present invention is to provide an exposure apparatus, and manufacturing method thereof, capable of performing favorable overlapping exposure by setting at nearly the same position in the focusing direction the portions that contribute to the formation of partially overlapping regions in the image planes of projection optical modules that are next to each other, even if the position of the image planes of each projection optical module should change because of thermal deformation of the lenses, for example.
A further object of the present invention is to provide an exposure apparatus, and manufacturing method thereof, capable of performing favorable exposure, even if the optical characteristics of each projection optical module should change because of thermal deformation of the lenses, for example, by adjusting the changed optical characteristics and correcting other optical characteristics, which may be worsened due to the adjustment.
A further object of the present invention is to provide a method of fabricating a favorable large area microdevice (e.g., a semiconductor device, a LCD device, a thin-film magnetic head, etc.) by performing favorable exposure utilizing an exposure apparatus of the present invention.
A further object of the present invention is to provide an exposure apparatus and an exposure method, capable of substantially suppressing (controlling) the changes in the optical characteristics of each projection optical unit due to optical absorption in lenses.
According to an aspect of the present invention, an exposure apparatus, comprising an illumination optical system, which illuminates a mask with a predetermined pattern, a projection optical system, which includes a plurality of projection optical modules that are arrayed in a predetermined direction in order to form partially overlapping exposure regions on a photo sensitive substrate, and projects the pattern of the mask onto the photosensitive substrate, and a focusing adjustment unit, which aligns each respective image plane of the plurality of projection optical modules with respect to the photosensitive substrate in a certain focusing direction, wherein the focusing adjustment unit sets at a substantially same position in the certain focusing direction, certain portions that contribute to formation of the partially overlapping exposure regions on image planes of projection optical modules that are next to each other.
According to another aspect of the present invention, an exposure apparatus comprising, an illumination optical system, which illuminates a mask with a predetermined pattern, a projection optical system, which includes a plurality of projection optical modules that are arrayed in a predetermined direction, and projects the pattern of the mask onto a photosensitive substrate, a first adjusting unit, which compensates a change of a first optical characteristic in accordance with time passage with respect to at least one projection optical module of the plurality of projection optical modules, and a second adjusting unit, which compensates a second optical characteristic that differs from the first optical characteristic and is caused by to the first adjusting unit.
According to a further aspect of the present invention, an exposure apparatus comprising, an illumination optical system, which illuminates a mask with a predetermined pattern, a projection optical system, which includes a plurality of projection optical modules that are arrayed in a predetermined direction, and projects the pattern of the mask onto a photosensitive substrate, a first adjusting unit, which compensates a change of an optical characteristic with respect to at least one of the plurality of projection optical modules that develop due to heat deformation of at least one optical component that is included in each of respective the plurality of projection optical modules, a second adjusting unit, which compensates a change of an optical characteristic with respect to of the plurality of projection optical modules that develop due to heat deformation of at least one deflecting member included in each of respective the plurality of projection modules.
According to a further aspect of the present invention, an exposure apparatus, comprising, an illumination optical system, which illuminates a mask with a predetermined pattern, and a projection optical system, which comprises a plurality of projection optical modules that are irradiated with light from said illumination optical system through the mask and arrayed in a predetermined direction, and projects the pattern of the mask onto a photosensitive substrate, wherein, in order to form a partially overlapping exposure region onto the photosensitive substrate, image planes of the plurality of projection optical modules have a portion that contributes to the formation of the overlapping exposure regions; and moreover, in order to make position of portions that contribute to formation of the overlapping exposure regions that are next to each other substantially the same in certain focusing direction, further comprising a focus adjustment unit that performs adjustment of each position in the certain focusing direction of image planes of the plurality of projection optical modules.
According to a further aspect of the present invention, an exposure apparatus manufacturing method, which exposes a pattern of a mask onto a photosensitive substrate using a projection optical system having a plurality of projection optical modules arrayed in a predetermined direction in order to form partially overlapping exposure regions on the photosensitive substrate, and an illumination optical system that illuminates the mask with a predetermined pattern, the exposure apparatus manufacturing method comprising, a measurement step of measuring position of image planes of the plurality of projection optical modules in a certain focusing direction, and an adjustment step of adjusting so that portions that contribute to the partially overlapping exposure regions of image planes of projection optical modules that are next to each other have substantially the same position in the certain focusing direction using measurement information that is obtained in said measurement step.
According to a further aspect of the present invention, an exposure apparatus manufacturing method, which exposes a pattern of a mask onto a photosensitive substrate using a projection optical system that has a plurality of projection optical modules arrayed in a predetermined direction and an illumination optical system that illuminates the mask with a predetermined pattern, the exposure apparatus manufacturing method comprising, a calculation step of pre-calculating a maximum positional change amount for image planes of the plurality of projection optical modules in a certain focusing direction, and a setting step of setting initial reference image planes of the plurality of projection optical modules based on calculated results of the calculation step.
According to a further aspect of the present invention, an exposure apparatus, comprising, an illumination system for illuminating each of respective plurality of regions in a predetermined direction, the regions are included in a pattern formed on a mask, and a projection optical system, which comprises a plurality of projection optical units arrayed corresponding to the plurality of regions on a mask, and projects the pattern that is formed on the mask to a photosensitive substrate, wherein the illumination system forms a secondary light source at a position substantially optically conjugate with each respective pupil plane of the plurality of projection optical units, and has a function for introducing the light from the secondary light source into said mask, and the illumination system comprises, in order to actually control changes in each respective optical characteristic of the plurality of projection optical units by optical illumination, a setting unit that sets the secondary light source for an optical intensity distribution that is actually higher intensity in peripheral portion therein than in center portion therein.
According to a further aspect of the present invention, an exposure apparatus, comprising, an illumination system, which illuminates each of a plurality of regions positioned in a given direction on a mask with a pattern, and a projection optical system, which has a plurality of projection optical units positioned corresponding to the plurality of regions on the mask, and which projects the pattern formed on the mask onto a photosensitive substrate, wherein the illumination system has a function to form a secondary light source in a position substantially optically conjugate with the pupil plane of each of the plurality of projection optical units, and to guide light from the secondary light source to the mask, and the illumination system comprises a setting unit, which sets the outer diameter of the secondary light source when it is converted to a value on the pupil plane, to greater than 0.7 times the clear aperture of the pupil plane, so that a change in the optical characteristics of each of the plurality of projection optical units, which is caused by irradiation of light, can be controlled for the most part.
According to a further aspect of the present invention, an exposure apparatus, comprising, an illumination system, which illuminates a mask with a pattern, and a projection optical system, which projects the pattern on the mask onto a photosensitive substrate, wherein the illumination system comprises a formation unit, which forms a secondary light source in a position substantially conjugate with the pupil plane of the projection optical system, and an adjustment unit, which adjusts the optical intensity distribution of the secondary light source dependent upon a change in the optical characteristics of the projection optical system.
According to a further aspect of the present invention, an exposure apparatus, which exposes a photosensitive substrate through a mask on which a pattern to be transferred is formed on a plurality of regions in a given direction, the exposure apparatus comprising, a projection optical system, which has a plurality of projection optical units respectively positioned corresponding to the plurality of regions, and which projects the pattern onto a photosensitive substrate, and an illumination system, which forms a secondary light source in a position substantially optically conjugate with the pupil plane of each of the plurality of projection optical units, and which illuminates the mask with light from said secondary light source, wherein the illumination system includes a setting unit, which sets a optical intensity distribution where a peripheral portion of the secondary light source has a higher intensity than that of a center portion, so that change in the optical characteristics of each of the plurality of projection optical units, which is caused by light from the secondary light source, can be controlled.
According to a further aspect of the present invention, an exposure method, which illuminates a plurality of regions, which are positioned in a given direction on a mask with a pattern, and then projection exposes the pattern formed on the mask onto a photosensitive substrate through a projection optical system with a plurality of projection optical units positioned corresponding to the plurality of regions on the mask, the exposure method comprising, an illumination step of illuminating a plurality of regions on the mask by forming a secondary light source in a position nearly optically conjugate with the pupil plane of each of said plurality of projection optical units, and then guiding light from said secondary light source to the mask, and a setting step of setting the optical intensity distribution of the secondary light source where its peripheral portion has a practically higher intensity than that of its center portion, so that change in the optical characteristics of each of the plurality of projection optical units, which is caused by irradiation of light, can be practically controlled.
According to a further aspect of the present invention, an exposure method, which illuminates a plurality of regions, which are positioned in a given direction on a mask, on which a pattern to be transferred is formed, and then projection exposes the pattern formed on the mask onto a photosensitive substrate through a projection optical system with a plurality of projection optical units positioned corresponding to the plurality of regions on said mask, the exposure method comprising, an illumination step of illuminating a plurality of regions on the mask by forming a secondary light source in a position nearly optically conjugate with the pupil plane of each of the plurality of projection optical units, and then guiding light from said secondary light source to said mask, and a setting step of setting the outer diameter of the secondary light source when it is converted to a value on said pupil plane, to greater than 0.7 times the clear aperture of the pupil so that change in the optical characteristics of each of the plurality of projection optical units, which is caused by irradiation of light, can be practically controlled.
According to a further aspect of the present invention, an exposure method comprising, an illumination step of illuminating a mask using an illumination optical system, and a transcription step of transcribing a pattern that is formed on said mask onto a photosensitive substrate, wherein the illumination step includes a step of making an optical intensity distribution at pupil of the illumination optical system higher a peripheral portion than a center portion, and the transcription step comprising, a first exposure step, which forms a first exposure region on the photosensitive substrate while making the optical intensity distribution at pupil of said illumination optical system higher the peripheral portion than the center portion, and a second exposure step, which forms on the photosensitive substrate a second exposure region that partially overlaps the first exposure region while making the optical intensity distribution at pupil of the illumination optical system higher the peripheral portion than the center portion.
According to a further aspect of the present invention, a microdevice manufacturing method comprises an exposure step of exposing the pattern image of the mask onto the photosensitive substrate using the aforementioned exposure apparatus, and a development step of developing the substrate exposed.
According to a further aspect of the present invention, an exposure apparatus includes, an illumination system that illuminates each of a plurality of regions positioned in a given direction on a mask, on which a pattern to be transferred is formed, and a projection optical system that has a plurality of projection optical units positioned corresponding to the plurality of regions on the mask, and which projection exposes the pattern formed on the mask onto a photosensitive substrate through the projection optical system. This illumination system comprises at least one light source, a light guide, which has the same number of incident end(s) as that of the light sources and the same number of emitting end(s) as that of the plurality of projection optical units, at least one relay optical system, which guides light from the at least one light source to the incident end of the light guide, a plurality of optical integrators, which form a secondary light source in a position nearly optically conjugate with the pupil plane of each of the plurality of projection optical units dependent upon luminous flux emitted from a plurality of emitting ends of the light guide; a plurality of capacitor optical systems, which guide luminous flux from the plurality of secondary light sources to the plurality of regions of the mask, respectively; and a setting unit, which sets the optical intensity distribution of the plurality of secondary light sources to a optical intensity distribution with its peripheral portion having a substantially higher intensity than that of its center portion, so that change in the optical characteristics of each of the plurality of projection optical units, which is caused by irradiation of light, can be practically controlled.
According to a further aspect of the present invention, an exposure apparatus includes an illumination system that illuminates each of a plurality of regions positioned in a given direction on a mask, on which a pattern to be transferred is formed, and a projection optical system that has a plurality of projection optical units positioned corresponding to the plurality of regions on the mask, and which projection exposes the pattern formed on the mask onto a photosensitive substrate through the projection optical system. This illumination system comprises at least one light source, a light guide, which has the same number of incident end(s) as that of the light sources and the same number of emitting end(s) as that of the plurality of projection optical units, at least one relay optical system, which guides light from the at least one light source to the incident end of the light guide; a plurality of optical integrators, which form a secondary light source in a position nearly optically conjugate with the pupil plane of each of the plurality of projection optical units dependent upon luminous flux emitted from a plurality of emitting ends of the light guide, a plurality of capacitor optical systems, which guide luminous flux from the plurality of secondary light sources to the plurality of regions of the mask, respectively, and a setting unit, which sets the optical intensity distribution of the plurality of secondary light sources when it is converted to a value on the pupil plane, to greater than 0.7 times the clear aperture of the pupil plane, so that change in the optical characteristics of each of the plurality of projection optical units, which is caused by irradiation of light, can be practically controlled.
The present invention will be more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by way of illustration only and are not to be considered as limiting the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will be apparent to those skilled in the art from this detailed description.